Hybrid electric vehicles generally use powertrain architecture that combine internal-combustion engines and batteries that power electric traction motors for propulsion. When vehicle speeds are low, vehicles are typically in a pure electric propulsion mode. When the vehicle speeds are high enough, internal-combustion engines are excited, and the electric traction motors can be actuated providing a torque boost to the driveline, charge to the main battery, driveline synchronization during gear shifts, and/or driveline active damping to improve driver feel. As commonly known, considerable improvements in fuel economy and emission reductions are achievable using hybrid electric vehicles.
As in any other physical systems, faults may occur during the operation of electric traction motor drives. Hence, it may be necessary to check the electric motor shut-off path effectiveness for each driving cycle. When ensuring that a motor shut off mechanism operates correctly, it is conventionally necessary to spin the electric motor. The motor is spun and the current induced by the moving magnets or windings can be measured. However, at the vehicle startup, spinning the motor for torque shutoff path check may be impossible in some instances, requires time and can cause audible noise that concerns drivers.